The international photographer (Feb-Dec 1929)

Twenty-eight The INTERNATIONAL PHOTOGRAPHER November, 1929 hitherto unrealized fields of view. In projection the Question of illumination bristles with difficulties. The Bausch and l.on.b Optical Company has been co-operating with the sponsors of wide film motion pictures by designing the new lenses involved. New photographic lenses which cover a picture area 2.'!x4G m.m. at a speed of f:2.3 in focal lengths as short as 50 m in., new projection lenses which will project, with beautiful definition, pictures of this size in focal lengths as short as :: inches, and new condensers to bring the brightness of the projected picture up to a satisfactory level have been perfected. Abstract THE OPTICS OF MOTION PICTURE PROJECTORS The optical system employed in a motion picture projector is considered on the basis of the conservation of energy principle. Equations are given from which the screen illumination can be computed for an ideal system froimt the brightness of the source and the constants of the lenses. This ideal system assumes lenses which are perfect 1\ corrected and which introduce no loss of light by absorption or reflection. Although such a system is unattainable in practice, it provides a basis by which the efficiency of any actual system can be rated. Abstract of The Academy of Motion Picture Arts and Sciences and Its Service as a Forum for the Industry. The Academy as a successful experiment in organization engineering has combined in a unified body the principal members of the several associated but diversified creative arts in the motion picture production industry on the basis of friendly co-operation for the common good. Among its activities four have a special interest to the technical departments: 1. Meetings are held for interchange of ideas and information among the different branches of production. 2. A joint comimiittee of producers and technicians may sponsor an extensive program of non-competitive research. ?,. The Academy in co-operation with other technical societies is serving as the medium for ion elation of several practices between studios and theatres. 4. A pioneering experiment in industrial education is now in progress. About 500 selected studio employes will have the benefit of class instruction by leading recording and reproduction authorities. The information supplied will also he made generally available in the form of reprints of papers. Abstract of SOUND MOTION PICTURES IN EUROPE N. D. Golden American talking motion pictures in Europe with the exception of England are according to N. G. Golden, assist chief. Motion Picture Division, Bureau of Foreign and Domestic Commerce, Washington, D. C, to some degree encountering difficulties where English is not the predominating language. On the other hand sound motion pictures with musical synchronization are finding considerable favor in the different countries of Continental Europe. Exports of American made motion pictures to foreign markets have increased rather than decreased with the advent of sound pictures abroad. Europe with approximately 27,000 theatres lias 1043 theatres with a seating capacity of 1000 and appromiately 8000 theatres seating from 500 to 1000, which are potential purchasers of sound equipment. The main problem, confronting European theatre ownes is the financial burden from installing the required apparatus for the showing of sound pictures. Relief in this direction, however, seems to be approaching with the recent announcement by certain large American manufacturers of a smaller apparatus and facilities for the financing of it. ture positive film for 20 minutes in order to eliminate the hypo. Under practical conditions the times are greater according as the conditions differ from the ideal. Abstract SOME NEW ASPECTS OF REVERBERATION Edward W. Kellogg Experience has indicated that for an auditorium of a given size there is an optimum value of reverberation time. Some of the beneficial effects of reverberation can he imitated by means of electrical sound equipment. Where davantage can he taken of this factor, it may prove desirable to increase acoustic absorption much beyond what is now considered the optimum value. Abstract of A METHOD OF TESTING FOR THE PRESENCE OF SODIUM THIOSULFATE IN MOTION PICTURE FILMS J. I. Crabtree and J. F. Ross Kodak Research Laboratories A method of testing for the presence of sodium thiosulfate in motion picture film has been worked out which consists of placing strips of processed films in a mercuric chloride-potassium bromide solution. If the film contains an appreciable quantity of sodium thiosulfate the solution becomes opalescent. the turbidity being, roughly proportional to the quantity of hypo present. It is possible to detect the presence of 0.05 milligrams of sodiuimi thiosulfate (crystals) in motion picture film by this test. Some of the factors which determine the rate of fading of silver images have been outlined and the critical hypo content and degree of washing necessary with negative and positive motion picture film to insure stabiliity have been indicated. Under ideal conditions it is necessary to wash thoroughly fixed motion picture negative film for 3o minutes and motion pic Abstract of October 7 to 10th, 1929 A NEW SIXTEEN MILLIMETERS MOTION PICTURE CAMERA By Joseph A. Dubray Chief of Technical Service, Bell & Howell Co. A new lGmm. camera, known as the "FILMO Model 7 0-D" has been presented to the amateur field by the Bell & Howell Company. Tin camera is of the spring motor type, has a capacity of one hundred feet of film, and each winding of the motor permits to uninterruptedly expose twenty-five feet of film. The camera is equipped with an integral turret head, capable of holding three lenses of different focal lengths, and a newly designed viewfinder, permitting a rapid change of masks which determine the field of view covered by any one of six lenses of focal lengths varying from 1 inch to ti inches. The median sm of the camera is described and stress is laid upon the features of the speed regulating governor, which is of an entirely new design and instantaneous in its action. The governor permits to operate the ca iea at speeds varying from a minimum of eight to a maximum of sixtyfour pictures per second, including all intermediate speeds. A device has been incorporated in this camera which, together with the governor, insures a positive start of the mechanism at any desired speed and an equally positive stop at all speeds, without sacrificing the features of the camera stopping with the shutter in its position of occultation, and without the slightest acceleration or deceleration being visible on the exposed film. .Mention is made of the lubrication system of the apparatus. William H. Daniels SAYS "I guess nearly everyone at M-G-M Studio is already doing business with Mr. Eschner, so that it isn't necessary for me to say very much regarding his plan. However, I am glad to have started ;my savings account." ALBERT ESCHNER PACIFIC COAST BLDG.-LOAN ASSN. 310 Taft Building, Hollywood, Calif. GRanite 1721 THE "INTERNATIONAL PHOTOGRAPHERS" RING This massive hand wrought gentlemen's ring specially designed for I. T. men In Solid Gold 14 Karat $25.00 In Solid Gold 10 Karat 20.00 In Solid Sterling Silver 10.00 With Black Onyx — Hand Hammered — Dressy and Durable — Designed and Made by J. A. MEYERS & CO., 822 So. Flower St. rrrrnTTTTTTi ^a*™^ I 234 5678010 1112 13]) _ _ LLLLLLLLLLL1J Manufacturers of your GOLD LIFE MEMBERSHIP CARDS Designers of the Smith & Aller Trophy, Etc. ring size tear off perforated strip ace around finger, bring A toward MaJtl orders given careful and prompt attention. Kindly send ching size. a one-third deposit, ring sent C. O. D. for the balance.